LOS ANGELES — Smoking raises the risk of diabetes, but new research indicates that — at least in the short term — kicking the habit increases the risk even more.
The problem is the pounds most people pack on when they give up cigarettes, Pennsylvania researchers report today in the Annals of Internal Medicine.
Smokers who plan to quit should be very careful not to start eating more and thus gain weight, said epidemiologist Hsin-Chien "Jessica" Yeh of the University of Pennsylvania, the study's lead author. But the most important message, she said, is, "Don't begin to smoke in the first place."
Yeh and her colleagues studied 10,892 middle-aged adults who were enrolled in a study to determine their risk of atherosclerosis, or hardening of the arteries. None had diabetes when they enrolled between 1987 and 1989.
Most were followed for an average of about nine years, and 1,254 developed Type 2 diabetes, which is usually associated with obesity and is characterized by the body's reduced ability to use insulin.
The study found that smokers had about a 40 percent higher risk of contracting diabetes than those who never smoked. "That is consistent with previous research from many studies saying smoking is bad," Yeh said.
Surprisingly, however, the risk increased when smokers quit, peaking at about a 70 percent increased risk in the first three years after quitting, then declining to normal risk after 10 years.
On average, those who quit smoking gained about 8.4 pounds during the three-year period and their waist size grew by 1 1/4 inches. The more weight they gained, and the longer they had been smoking, the higher their risk of developing diabetes.
The team is not sure why the risk eventually fell back to normal after 10 years, Yeh said. They did not measure the patients' weights at that time, so they don't know whether they lost weight or if some other factor was involved.
She emphasized that smokers should not use the findings as an excuse to keep smoking because the risks of increased heart disease, strokes and cancer linked to smoking far outweigh the small increase in risk for diabetes.
But physicians who encourage their patients to quit smoking should also work with them to prevent weight gain, she said.